This invention relates in general to a method and apparatus for removing sulfur from coal and, more particularly, to such a method that employs microwave energy to cause the release of the sulfur from the coal and removes the gaseous sulfur from the atmosphere surrounding the coal by applying a vacuum and by mixing an adsorbent material with the coal, and an apparatus adapted to perform such method.
The environmental problems associated with the burning of high-sulfur coal are well documented. One of the most significant problems is the release of sulfur dioxide into the atmosphere during the burning process which contributes to the effects of acid rain. In an attempt to reduce the effects of acid rain and other environmental problems associated with the burning of high sulfur coal, governmental regulations have been enacted which limit the amount of sulfur dioxide that can be emitted from a facility, such as a power plant, utilizing coal as an energy source. These regulations are most readily followed by utilizing .low sulfur containing coal. Unfortunately, much of the coal located in the Midwestern and Eastern portions of the United States is considered high sulfur coal and cannot be effectively utilized within the governmental regulations. This fact drastically limits the use of a significant amount of the coal reserves in the United States as an energy source.
Various methods have been proposed to remove or reduce the level of sulfur in high sulfur coal. None of these methods have, however, received widespread acceptance within the coal industry because they are either ineffective or too expensive for commercial use. One conventional solution, the use of wet-scrubbers or dry-scrubbers to treat the sulfur gases emitted during the burning of high sulfur coal, has proved to be extremely costly and not altogether acceptable in terms of solving the sulfur emission problem. Other methods employing chemical treatment of the coal to separate the sulfur from the coal have been developed, but have generally proved to be ineffective or too costly to pursue on a large scale. There is, therefore, a need in the coal industry for an effective and economical method for desulfurizing coal on a large scale and an apparatus that facilitates the practice of such method which overcome the foregoing problems.